Fasteners, clips, anchors and holding devices of different designs have a variety of applications in various structures and assemblies for securing one or more parts of the assembly to other parts of the assembly. Fasteners and clips are used extensively in the automotive industry for securing panels and components to structural members. For example, clips are used to secure interior panels to frame or support members. Clips also are used for securing wires, brake lines, fuel lines and other elongate members at selected locations along the lengths thereof. Such holding devices are configured in a variety of different arrangements depending on the locations in which the device will be installed, the types of articles and things to which the device will be secured, the item designed to be held and the requirements of strength and security for use.
In a known construction, a holding device such as a fastener or clip is secured in an opening or hole of the object to which is attached. Opposed, spaced deflectable members are configured and arranged to deflect toward each other as the holding device is inserted into the hole, and to rebound away from each other after a portion of the deflectable member has passed through the hole. Ledges or other formations on the deflectable members abut a surface adjacent the hole on a side of the hole that is opposite to the side from which the prong was inserted. The ledges or other formations inhibit extraction from the hole by resisting inward deflection of the deflectable member when extraction force is applied.
Holding devices as described above have advantages in that they can be attached relatively quickly and easily by simply being pushed into the hole by hand or mechanically. The holding device is fixed automatically in the installed position on the object. Such holding devices have achieved acceptance for use in so-called “blind attachments”, where the item to be held is first attached to the holding device or devices, and the device or devices are then positioned over the holes in the anchoring object and pushed into the hole or holes. Such assemblies can be completed even when the hole of the object to which the holding device will be anchored is not readily visible from the front side or accessible from the back side thereof. Accordingly, such holding devices have been used successfully in many applications.
However, such holding devices are not completely without inadequacies, and improvements thereto are desirable. For example, in some installations and uses it is desirable that the holding device be relatively easy to insert, with little resistance, yet offer significant resistance to removal. It is sometimes difficult to achieve the desired ease of insertion for the holding device with the desired resistance to extraction. Prongs that are easily deflected for insertion tend also to deflect easily when extraction force is applied. Further, it is known that forces acting on the holding device can cause one or less than all of the anchor prongs to bend away from the other prong or prongs, beyond the natural position thereof, in the opposite direction from the direction of deflection for insertion. If bent to an extreme position the prong or prongs can break, rendering the holding device unstable, and perhaps causing demounting of the holding device from the object to which it is attached.
What is needed is a pronged anchoring structure for a holding device having low force required for insertion yet significant resistance to forces toward extraction of the fastener.